Selectively responsive device



F. H. HIBBARD SELECTIVELY RESPONSIVE DEVICE Oct. 26, 1948.

2 Sheets-Sheet 1 Filed Dec. 50, 1946 INVENR V ATTORNEY Patented Oct. 26,1948 SELECTIVELY RESPONSIVE DEVICE Frank H. Hibbard, Mountain Lakes, N.J assignor to Bell Telephone Laboratories, Incorporated, New York, N.Y., a corporation of New York Application December 30, 1946, Serial No.719,274

This invention relates to selectively responsive devices and moreparticularly to electromagnetically actuated mechanisms which areselectively responsive to one, and only one, of several differentcombinations of a. given number of digits having numerous combinationsof pulses therein.

Heretofore in connection with selectively responsive devices ormechanisms of the electromagnetically actuated type the selection hasbeen accomplished by means of different polarities of pulses, diiferentamplitudes of pulses, different pulse widths, different time intervalsbetween pulses and others comprising various combinations of thesesomewhat basic means. The present invention is concerned with what ispreferred to be called a digital code system wherein a series ofconsecutive groups of pulses is transmitted to several devices. -Eachgroup of pulses comprises a plurality of individual pulses, the onlylimitation on which is that the pulses of each of the said groups beseparated by not more than a given amount of time. The only limitationupon the series of groups is that the consecutive groups of said seriesbe separated by not less than a given amount of time, the latter amountof time being slightly larger than the former mentioned amount of time.The device to which the series of groups of pulses is transmitted isadapted to respo y signalling or otherwise, to only one series of groupswherein there are a certain prearranged number of pulses for each groupand the groups are transmitted in a certain prearranged sequence.

Heretofore devices selectively responsive to a digital code have beenrestricted in their versatility in that irrespective of the number ofdigits or pulse groups transmitted and irrespective of the maximumPossible number of pulses in any one group these devices have beenrestricted to respond satisfactorily to less than the theoreticallypossible maximum number of digital codes available from such a system.The restriction was in general that the devices could respond only to aseries or groups of pulses, or series of digits,

wherein the total pulse content of the series was less than thetheoretical maximum number of pulses available for such a series fromthe sys tem employed.

It is one feature of the present invention to provide a mechanism of theclass mentioned above which is capable of responding satisfactorily to adigital code regardless'of the number of digits in the series of sameand irrespective of the number of pulses in any digit or group of thesaid series. For instance, as disclosed herein byexample. a

13 Claims. (Cl. 177-353) digital code system employing four digits. witha possible maximum of ten pulses per digit presents ten thousandpossible different codes using the four digits in all possiblecombinations and withall possible pulse contents of each digit. Theinventlon herein disclosed is capable of selectively responding to anyone of these ten thousand codes while being incapable of responding toany other of the codes while adjusted to respond to the said one of saidcodes. The present exemplary disclosure of the invention is thereforecapable of responding to an unrestricted four-digit code, the wordunrestricted, as it is used herein, meaning not restricted in itscapability of responding to any one of the possible maximum number ofcodes as previously explained. V

In the exemplary disclosure set forth herein two parallel ratchetcarrying cam shafts are individually stepped by separate electromagneticmotor mechanisms. The two motor mechanisms are subjected to all pulsesof all digits of the said code. One cam shaft is designated the digitcam shaft and comprises four hooks equally spaced longitudinally of theshaft and spaced one ratchet step from each other circumferentially ofsaid shaft and in a helical formation along the axis of said shaft. Thisdigit cam shaft is stepped by a slow-to-release electromagnetic motormechanism arranged to release only upon a time duration between pulsesrepresented by the lapse of time between digits or a greater time lengthand will not release in the time between pulses of any one digit. Thesecond cam shaft is designated the pulse cam shaft and comprises fourcams having a raised portion on each equally spaced longitudinally ofthe shaft and opposite the said hooks on the digit cam shaft. Thecircumferential positions of the cams is arbitrary depending on the codeto which the device is to respond as will be fully explainedhereinafter. The digit shaft contains a cam adapted to move a contactspring when said digit shaft has been stepped four cumulativelysuccessive ratchet steps. There are four resilient spring membersadjacent the four pulse cams respectively, each member being adapted,when depressed by its respective pulse cam, to assume a positionrelative to the digit shaft such that if the respective digit shaft hookis in suitable position thereto the member will engage same and retainthe digit shaft in its advanced position. The pulse shaft is stepped onestep for each pulse of each digit, the digit shaft being stepped oncefor each digit. If the pulse content of the first digit is correct so asto position the first spring member to retain the digit member islikewise suitably positioned to retain the digit shaft for each of foursuccessive steps, the cam on the digit shaft will be brought to aposition where it can move a contact spring and effect a signalindicating response to a ve digital code.

The invention briefly set forth above is discussed in detail hereinafterwith the assistance of the drawings forming a part of this disclosure,of which:

Fig. 2 is a side view of an exemplary embodiment of the invention shownas part of a signaling system in which the invention is employed torespond selectively to one of a possible plurality of digital codestransmitted thereto, to thereby effect a signal that the full responsehas been accomplished; 4

Figs. 1, 3 and 4 are respectively top elevation, front elevation andrear elevation views of the device shown in Fig. 2;

Figs. 5 and 6 are brief detailed sketches taken along the lines 5-5 ofFig. 1 and simplified to illustrate more clearly an operational featureof the invention; and

Figs. 7 and 8 are brief detailed sketches taken along'the line 11 ofFig. l and simplified to illustrate more clearly another operationalfeature of the invention.

The operating mechanism of Figs. 1 through 4 is attached to and confinedby two main side re- 4 taining plates and 2. In Fig. 2 an electromagnet3, having a copper slug 4 thereon, is attached by means of itsheel-piece 5 to retaining plate 2. the plate I having been removed toexpose the mechanism for reference. This magnet 3 will be referred tohereinafter as the digit magnet 3. An' armature 6 is provided for thedigit magnet 3 and is attached to a plate 1 pivoted on the heelpiece 5by pin 8. The plate 1 has integral therewith two arms 9 and I0, moreclearly shown in Fig. 3. These arms 9 and III are joined by a bar H atthe tops or free ends of said arms, the bar normally resting against aback stop member l2. Attached to the retaining plates I and 2, or frameas these retaining plates shall be referred to, by means of a crosspiecel3 are four vertical resilient strips or rods l4, l5, l6 and H which arepretensioned to bear against the bar II at the top of the arms 3 and I]!to bias this armature assembly against the back stop l2. Fig. 3illustrates these four rods or strips l4 through |1 most clearly. Pinhinged to the upper ends of the rods l4 through l1, such as by pin l3for rod l4, are four horizontal fingers 9, 20, 2| and 22 guided byslots, such as 23, in the bottom ofa guide plate 24 attached to theframe I, 2.

When the digit magnet 3 is energized a drive pawl 25 on arm 9 of thearmature'assembly for magnet 3 will engage ratchet wheel 25 on the camshaft 21. A spacing pawl 23, also on arm 9', will engage ratchet 29,also on cam shaft 21,'to permit only a certain amount of rotation of theshaft 21 for each step of the magnet 3. As the arms '3 and "I are moveddue to energization of magnet 3 the bar II will push on the tops of rodsl4 through l1 and thus slide the fingers l9 through 22 to the right inFig. 2. as will be explained in more detail hereinafter in connectionwith Figs. '1 and 8.

A lever 33 pivoted to the frame at 3| is biased to the position shown inFig. 2 by pin-32' on arm II. In this position an insulated knob 33 onthe end of said lever 33 depresses a contact spring 34 clearly in Fig.1, that the retaining pawl 52 is against its natural resilience. Thuswhen the magnet 3 is energized to move arms 8 and ID, the lever 30,under the action of the resilience in contact spring 34, will turn aboutits pivot 3| to permit the contact spring 34 to rise. Contact spring 34cooperates with contact spring 35 in the pile-up section 33 to ring abell 31 or other signal as will hereinafter be described withparticularreference to Figs. 5 and 6;

After the cam shaft 21 has been stepped there -is no retaining means tohold it advanced against the action of the spiral spring 38 except ashereinafter described. The shaft 21 will tend to return to its normalposition determined by a lug 39 thereon engaging a stop pin 40 on theframe as shown in Fig. 2.

A magnet 4|, which may be referred to as the pulse magnet, is attachedto retaining plate 2 and has an armature 42 with extension 43 thereforand a spring 44 adapted to bias armature extension 43 to the positionshown in Fig. 2 against the back stop 45. A front stop 46 is provided tolimit the movement of extension 43 when the pulse magnet 4| isenergized.

Similarly to the previous discussion concerning the ratchets 26- and 29on cam shaft 21, the armature extension 43 carries a stepping or drivepawl 41 and a spacing pawl 48 adapted respectively to engage ratchets 49and 50 on cam shaft 5| to step said shaft a given amount for eachenergization of the pulse magnet 4|. Ratchet 49 on cam shaft 5|, unlikeratchet 26 on cam shaft 21, has a retaining pawl 52 adapted to retainthe advanced movement of the cam shaft 5| against the action of spiralspring 53. It is to be noted, most engaged by a hook member 53, attachedto finger Hi, When the fingers l9 through 22 are allowed to move to theleft of Fig. 1 upon release of the digit magnet 3. This hook member 53will retract the retaining pawl 52 from its engagement with ratchet 49and thereby allow the cam shaft 5| to return to normal where a lug 54 onsaid shaft engages a stop pin 55 on the framework.

In the pile-up assembly 56 of Fig. 2 are mounted four sets of springfingers, such as 51 and 58, more clearly shown in Figs. 7 and 8.

Spring fingers such as 58 are resiliently biased to rest against a stopmember 59 attached to the frame. Spring fingerssuch as 51 areresiliently biased to rest against the 'cam surfaces of the cams such as60 on cam shaft 5|, there being four cams 60, GI, 62 and 63, per Fig. 4,each of which cooperates in the above manner with a set of springfingers, such as described above in connection with fingers 51 and 58shown in Figs. 7 and 8. The ends of the bottom spring fingers such as58, are adapted to engage hooks, such as 64, on the cams of cam shaft 21but will so engage these hooks 54 only when the fingers, such as l9,have been-moved to the position shown in Fig. 8 by the action of thedigit magnet 3 and associatedstepping mechanism and only when therespectively associated raised portion 65 of cams, such as 50, on camshaft 5| have been positioned in accordance with Fig. 8 due to theaction of the pulse magnet 4| and its associated stepping mechanism.

The cams of cam shaft 21 such as 55, 61, 38 and 53 of Fig. 4, each carrya hook, such as 64 of Fig. 7, the hook of each successive cam such as 51being one ratchet step beyond the hook on the preceding cam such as 66.The raised portions of the cams on cam shaft 5| may be arranged in anyrelative manner desired as long as they will be moved to positionscorresponding to that of Fig. 8 on a given number of full ratchet stepsof ratchet 43. Referring to Fig. 8.the hook 64 when advanced by thedigit magnet will be advanced slightly counterclockwise of the positionshown in Fig. 8 such that the spring member 53 may be positioned againstthe cam surface 66 to thereby catch hook 64 when the shaft 21 isreleased at the end of that particular digit.

The cam shaft 21 carries a fifth cam 10, shown in Figs. 3 and 4 and moreclearly in Figs. 5 and 6. If each of the four hooked cams of the camshaft 21 has been retained by the fingers, such as 58 of Fig. 8, eachtime the digit magnet 3 releases, the raised portion H of cam will beheld in the position shown in Fig. 6. When the digit magnet 3 releasesthe arm III, the pin 32 attached thereto will force lever to pivot about3| such that the insulated knob 33 thereon will depress contact spring34 into contact with contact spring now held upraised against its owntension by the portion 1| of cam 10. This contact of springs 34 and 35will complete a circuit for bell 31 through battery 12, of Fig. 2, toindicate a correct and full response of the device to the digital codesabout to be discussed.

Let it be assumed that it is desired that this particular device beresponsive to a digital code comprising four successive digitscontaining, respectively the numbers of pulses of 3l048. The cam 60 oncam shaft 5| would be set to come to the position shown for it in Fig. 8on three ratchet steps of ratchet 43 which corresponds to three separateenergizations and releases of pulse magnet 4| in responding to threepulses of this digit. It will be noted from Fig. 2 that the digit magnet3 is in parallel with the pulse magnet 4| to the source of digital codes13, such as th sources of code 3-10--4-8 assumed for purposes ofdiscussion. The digit magnet 3, however, is provided with a copper slug4, the effect of which is well known to make this magnet slow releasing.Let it sufilce to say that digit magnet 3 is arranged or adjusted torelease in the time between digits but will not release between pulsesof any one digit, this being a well-known phenomenon. Digit magnet 3will operate its stepping mechanism on the first pulse of every digitand release between digits, so that regardless of the number of pulsesin a digit the cam shaft 21 receives only one step per digit. The secondcam iii of cam shaft 5| will be arranged to assume the position of Fig.8 upon ten steps from its normal position. Likewise cams 62 and 63 willbe arranged to assume the indicated position on four and eight pulsesrespectively from normal positions, it being remembered that after eachdigit, the hook member 53 operated by the digit magnet steppingmechanism releases the retaining pawl 52 of ratchet 43 and allows thecam shaft 5| to return to normal from whence it starts for each digit ofthe code. a

When the first digit is transmitted the cam shaft 21 will step one stepthus positioning its first cam hook, such as 64 on cam 66 of Fig. 8, inposition to be engaged by aspring, such as 58, providing the number ofpulses in the digit corresponds to the cam setting of cam 60, aspreviously discussed in connection with Figs. 7 and 8. As previouslypointed out the cam hook 64 will be positioned slightly morecounter-clockwise than as shown in Fig. 8 to enable the spring member 53to be depressed into contact with cam 66. This is so that the springmember 53 may catch hook cam 64 when the shaft 21 is released at the endof the particular digit, by the release of the digit magnet. In theassumed case cam 66 was preset to assume the position indicated in Fig.8 upon three ratchet steps of the cam shaft 6|. The end result of thisoperation is that at the end 'of three pulses, spring member 53 will'bedepressed according to Fig. 8 such that when the digit magnet steppingmechanism releases, the spring 53 will engage the hook 64 to hold thecam shaft 21 advanced one step. The digit magnet stepping mechanism inreleasing permits the cam shaft 6| to return to normal as has beendiscussed.

Since cam 6| was preset for ten pulses itsspring member will engagethe'hook of cam 81 on shaft 21, which was brought into proper positionby the second operation of digit magnet 3 since this hook of cam 31 isone ratchet step beyond the hook of cam 63. Thus at the end of thesecond digit the cam shaft 21 is held advanced two steps. Likewisewithout further. discussion it is stated that at the conclusion of thefourth digit, since the pulse cams 60 through 63 have been properlypreset, the cam shaft 21 will have been advanced and held advanced fourcomplete cumulatively successive ratchet steps. It will be rememberedthat this result is the one which will bring the cam 1| into theposition shown in Fig. 6 and thus to effect the ringing bell 31 or othersignalling means by completing a circuit through battery 12 to thesignalling means 31.

From the foregoing discussion it is seen that the digit cam shaft 21will be restored to normal whenever the digit magnet 3 releases at endof each digit unless the number of pulses in the digit corresponds withthe preset angular position of the corresponding pulse cam such as 60.To restore cam shaft 21 to normal from its fourth step position per Fig.6, therefore, requires only that the code source 13 transmit a digit ofpulses different in number from that for which the fourth pulse cam 63is preset. By translating the code in transmission so as to use anynumber of pulses, such as 2 to 11 to represent code numbers such as 1 to10, it is possible to avoid presetting the fourth or any pulse cam inany selector to reach the position of Fig. 8 after a single pulse.

By this means, the cam shafts of any or all sev lectors connected to thecode source 13, can be restored to normal from the ringing position ofFig. 6 or from any other off-normal position by transmission from thesource 13 of a single impulse. This provision is also desirable in orderto prevent response of this device to any spurious single pulses such asmight be transmitted to the magnets by static or lightning or the like.This requirement of non-response to a single pulse is of practicalcommercial significance only since the response of the mechanism neednot be so limited or restricted if spurious pulses, such as mentionedabove, be ignored and if mechanical releasing means is provided at thelocality of the mechanisms for reverting the digit cam shaft 21 tonormal when preparing to receive an additional 7 a A block I is shown onFig. 2 and is intended to designate other selective devices-receivingthe same codes as transmitted by the source 13 to the mechanism of Fig.2. It .is to be understood that this block 15 may represent 9,999othermechanisms for a system of digital codes comprising four digitswhere each digit may consist of one to ten pulses and may representother quantities depending on the number of digits in the systememployed.

It is further to be noted that the invention is not limited in scope toa four-digit system but is readily adapted to systems of more or lessthan four digits provldingthe correct number of digit and pulse cams areprovided in accordance with the previous discussion concerning theexemplary disclosure herein of a mechanism adapted for a four-digitsystem.

Furthermore, although I have disclosed the interconnection of thereceiving devices with the source of codes as a wire connection, it isobvious that radio transmission is contemplated as well since pulsetransmission and reception by radio or wireless means is well known.

he fact that I have disclosed a bell 31 O1)- erated by the contact ofcontact springs 34 and I! to complete a circuit for the bell throughbattery 12 is also merely exemplary of a vast number and variety ofsignalling means well known and suitable for the purpose disclosed. Forinstance a relay could be operated which in turn might do further workor a vacuum tube could be activated or a motor energized. There will bemany such devices or means suggested by this disclosure, I

Having described the invention fully hereinbefore and not wishing thescope thereof to be limited to the specific exemplary disclosure used, Iappend the following claims which alone define the scope of theinvention. 1

What is claimed is: i

1. A selectively responsive device adapted to respond to all codes of aplural-digit code system and adapted to enable operation of a signalcircult in responding to only one of said codes, said A devicecomprising two shafts, each shaft having cams thereon, mechanism forrotating each shaft, one shaft rotatably responsive to each pulse ofeach digit ofsald code. the other shaftrotatably responsive to only thefirst pulse of each digit of said code, means for testing simultaneouslythe positions of at-least one cam of each shaft after rotationalresponse thereby to each digit, the positions'of said cams on saidshafts being predetermlnedand preset in accordance with the code desiredto effect enabling of said signal circuit,'said means operative, whensaid tested cams aresuccessively in the proper preset positions uponeach such test for each digit of said code, to enable operation of saidsignal circuit.

2. A selectively responsive device adapted to respond to all codes of aplural-digit code system and adapted to enable operation of a signalcircuit in responding to only one of said codes, said device comprisingtwo shafts, each shaft having cams thereon, spring means for biasingeach shaft to its normal position, rotating mechresponse of each shaftto each digit, the positions of said cams on said shafts beingpredetermined and preset in accordance with the code desired to effectenabling of said signal circuit, said means operative, when said testedcams are in the proper-preset positions upon each suchshaft rotatedcumulatively in response to each pulse of each digit of the said code,and returned to normal after each digit, the other shaft rotated inresponse to only the first pulse of each dish. of the said code, meansfor testing simultaneously the positions of at least one cam of eachshaft after rotational response of each shaft to each digit, thepositions of said cams on said shafts being predetermined and preset inaccordance withthe code desired toeffect enabling of said signalcircuit, said means operative, when said tested cams are in the properpreset positions upon each such test for each digit of said code, toretainsaid other shaft cumulatively advanced after each digit to therebyenable a cam on said other shaft to enable closing of said contactsprings to complete said signaling circuit after said two shafts haveresponded to all digits of said code.

4.-A selectively responsive device adapted to respond to all codes of aplural-digit code system and adapted to enable operation of a signa1circult in responding to only one of said codes, said device comprisinga first shaft, a plurality of first cams on said first shaft, a secondshaft, a plurality of second cams on said second shaft, said second camspreset in accordance with the code desired to enable the signal circuit,spring means for biasing said shafts to their normal positions, astepping mechanism for said first shaft adapted to step said-first shaftonce per digit of said code, a stepping mechanism for said second shaftadapted to step said second shaft once per pulse of each digit of saidcode, means for retaining said second shaft advanced after each pulse ofeach digit, means for releasing said second shaft after each digit ofsaid code, additional means cooper-able with one cam of each shaft toretain said first shaft successively in its advanced positions when bothstepping mechanisms have released, means actuated by said first shaftand adapted to enable operation of a. signalling means only when saidfirst shaft has been retained in successive advanced positions upon theplurality of consecutive digits of said code.

5. An electromagnetic selectively responsive device adapted to respondto all codes of an unrestricted plural-digit code system and adapted toenable closin of contacts in a signal circuit in responding to only oneof said codes, said device comprising two shafts, each shaft providedwith a plurality of cams, a ratchet on each shaft, spring means forbiasing said shafts to their normal positions, a stepping mechanism forone of said shafts and adapted to step said one shaft once per digit ofsaid code, a stepping mechanism for the second of said shafts andadapted to step said second shaft once per pulse of each digit of saidcode, means for retaining the advance of said second shaft after eachpulse of each digit, means actuated by said stepping mechanism for saidone shaft to release said second shaft retaining means after each digitof said code, members located adjacent the cams of said second shaft andadapted to be actuated by said cams, when said cams are stepped intoengagement therewith, to retain said first shaft in its advancedposition when both stepping mechanisms have released, at least one ofsaid cams of said first shaft adapted to enable the closing of saidsignalling contacts only when said first shaft has been retained insuccessive advanced positions upon the plurality of consecutive digitsof said code.

6. An electromagnetic selectively responsive device adapted to respondto all codes of an unrestricted plural-digit code system and adapted toenable closing of contact springs in a signal circuit in responding toonly on of said codes, said device comprising a first shaft providedwith a first ratchet and a plurality of first cams, a second shaftparallel to said first shaft and provided with a second ratchet and aplurality of second cams respectively adjacent said first cams, springmeans for biasing said shafts to their normal positions, electromagneticstepping motor mechanism for said first shaft adapted to step said firstshaft once per digit of said code, electromagnetic stepping motormechanism for said second shaft adapted to step said second shaft onceper pulse of each digit of said code, ratchet retaining means for saidsecond ratchet to retain the advance of said second shaft after eachpulse of each digit, means actuated by said stepping mechanism for saidfirst shaft andadapted to release said second ratchet retaining meansafter each digit of said code, resilient sprin members actuated by saidsecond cams when said second shaft has been stepped a number of ratchetsteps corresponding to the circumferential positions of the said secondcams, said spring members adapted, when actuated, to engage saidrespectively adjacent first cams to thereby retain said first shaft inits advanced position when both electromagnetic stepping mechanisms havereleased, the last cam of said first cams adapted to enable contactbetween said contact springs when the said first shaft has been retainedin successive advanced positions upon consecutive digits of said code tothereby enable completion of said signaling circuit;

'7. An electromagnetic selectively responsive device adapted to respondto all codes of an unrestricted plural-digit code system and adapted.

to enable closing of contact springs in a signal circuitin responding toonly one of said codes, said device comprising a, first shaft providedwith a first ratchet and a plurality of first cams arranged about saidfirst shaft such that each successive cam is one ratchet step beyond itsimmediate predecessor and the first of said first cams is one ratchetstep beyond the normal position of said first shaft, thelast two of saidfirst cams being circumferentially adjacent, a second shaft providedwith a second ratchet and a plurality of second cams, each of the saidsecond cams located circumferentially of said second shaft a number offull steps of said second ratchet from the normal position of saidsecond ratchet carrying shaft, spring means for biasing said shafts totheir normal positions, an electromagnetic stepping mechanism for saidfirst shaft adapted to step said first shaft once per digit of saidcode, an electromagnetic stepping mechanism for saidsecond shaft adaptedto step said second shaft once per pulse of each digit of the said code,ratchet retaining means for said second ratchet to retain the advance ofsaid second shaft after each pulse of each digit, means actuated by saidstepping mechanism for said first shaft and adapted to release saidsecond ratchet retaining means after each digit of said code, resilientspring members located adjacent said second cams and adapted to bedepressed by said second cams when said second shaft has been stepped anumber of ratchet steps corresponding to the circumferential positionsof said second cams, said spring members adapted, when depressed, toengage said first cams to thereby retain said first shaft in itsadvanced position when both electromagnetic stepping mechanisms havereleased, the last cm of said first cams adapted to actuate one of saidcontact springs only when said first shaft has been retained insuccessive advanced positions upon consecutive digits of said code andthe other of said contact springs adapted to be moved into electricalcontact with said one contact spring upon release of stepping mechanismfor said first shaft to thereby enable completion of said signalingcircuit.

8. An electromagnetic selectively responsive device adapted to respondto all codes of an unrestricted plural-digit code system and adapted toenable closing of contact springs in a signal circuit in responding toonly one of said codes, said device comprising a first shaft providedwith a first ratchet and a plurality of first cam surfaces arrangedhelically about said first shaft such that each successive cam surfaceis one ratchet step beyond its immediate predecessor and the first ofsaid first cam surfaces is one ratchet step beyond the normal positionof said first shaft, the last two of said first cam surfaces beingcircumferentially adjacent, a second shaft parallel to said first shaftand provided with a second ratchet and a plurality of second camsurfaces respectively adjacent said first cam surfaces, each of saidsecond cam surfaces located circumferentially of said second shaft anumber of full steps of said second ratchet from the normal position ofsaid second shaft, spring means for biasing said shafts to their normalpositions, a slow releasing electromagnetic stepping mechanism for saidfirst shaft adapted {to step said first shaft once per digit of saidcode, a fast releasing electromagnetic stepping mechanism for saidsecond shaft adapted to step said second shaft once per pulse of eachdigit of said code, ratchet retaining means for said second ratchet toretain the advance of said second shaft after each pulse of each'digit,means actuated by said stepping mechanism for said first shaft andadapted to release said second ratchet retaining means after each digitof code, a resilient spring member located beneath each second camsurface and adapted to be depressed by said second cam surface when saidsecond shaft has been stepped a number of ratchet steps corresponding tothe circumferential position of said second cam surface, said springmember adapted, when depressed, to engage the respective first camsurface adjacent said second cam surface to thereby retain said firstshaft in its advanced position when both electromagnetic steppingmechanisms have released, the last of said first cam surfaces adapted toraise one of said contact springs only when said first shaft has beenretained in successive advanced positions upon consecutive digits ofsaid code and the other of said contact springs adapted to be moved intoelectrical contact with said one contact springupon release of saidstepping mechanism for said firstshaft to thereby enable completion ofsaid signalling circuit.

9. An electromagnetic selectively responsive device adapted to respondto all codes of an unrestricted plural-digit code system and adapted toenable closing of contact springs in a signal circuit in responding toonly one of said codes, said device comprising a first shaft providedwith a first ratchet and a plurality of first cams equally spaced alongthe axis of said first shaft, all but the last one of said first camscomprising hooks opening along the same circumferential direction ofsaid first shaft and arranged helically about said first shaft such thateach successive hook is one ratchet step beyond its immediatepredecessor and the first of said hook cams is one ratchet step beyondthe normal position of said first shaft, the last of said first camshaving a raised portion adjacent the last of said hook camscircumferential of said shaft, 9. second shaft parallel to said firstshaft and provided with a second ratchet and a plurality of second camsequally spaced along the axis of said second shaft and respectivelyadjacent said first hook cams, each of said second cams having a raisedportion located circumferentially of said second shaft a number of fullsteps of said second ratchet from the normal position of said secondshaft, spring means for biasing said shafts to their normal positions, aslow releasing electromagnetic stepping mechanism for said first shaftadaptedto step said first shaft once per digit of'said code, a fastreleasing electromagnetic stepping mechanism for said second shaftadapted to step said second shaft once per pulse of each digit of saidcode, ratchet retaining means for said second ratchet to retain theadvance of said second shaft after each pulse of each digit, meansactuated by the stepping mechanism for said first shaft and adapted torelease said second ratchet retaining means after each digit of saidcode, a resilient spring member located beneath each second cam andadapted to be depressed by the raised portion of said respective secondcam when said second shaft has been stepped a number of ratchet stepscorresponding to the circumferentialposition of said raised portion ofsaid respective second cam, said spring member adapted when depressed toengage the hook of said first hook cam adjacent said respectivesecondcam to thereby retain said first shaft in its advanced positionwhen both firstshaft to thereby enable completion of said signalingcircuit.

10. An electromagnetic selectively responsive device adapted to respondto all codes of an unrestricted four-digit code system and adapted toenable closing of contact springs in a signal circuit in responding toonly one of said codes, said device comprising a first shaft providedwith a first ratchet and five first cams equally spaced 'along the. axisof said first shaft, the first four of said first cams comprising hooksopening along I 'spaced along the axis of said second shaft andrespectively adjacent said first hook cams, each of said second camshaving a raised portion located circumferentially of said second shaft2. number of full steps of said second ratchet from the normal positionof said second shaft, spring means'for biasing said shafts to theirnormal 'positions, a slow releasing electromagnetic stepping mechanismfor said first shaft adapted to step said first shaft once per digit ofsaid code, a fast releasing electromagnetic stepping mechanism for saidsecondshaft adapted to step said second shaft once per pulse of eachdigit of said code,-

ratchet retaining means for said second ratchet to retain the advance ofsaid second shaft after each pulse of each digit, means actuated by saidstepping mechanism for said first shaft and adaptedto release saidsecond ratchet retaining means after each digit of said code, aresilient spring member located beneath each second cam and adapted tobe depressed by the raised portion of said respective second cam whensaid second shaft has been stepped a number of ratchet stepscorresponding to the circumferential position of said raised portion ofsaid respective second cam, said spring'member adapted when depressed toengage the hook of said first cam adjacent said respective second cam tothereby retain said first shaft in its advanced position when bothelectromagnetic stepping mechanisms have released, said raised portionof the last of said five first cams adapted to raise one of said contactsprings but only when said first shaft has been retained in successiveadvanced positions upon four consecutive digits of said code and theother of said contact spring adapted to be moved into electrical contactwith said one contact spring upon release of said stepping mechanism forsaid first shaft to thereby enable completion of said signaling circuit.

11. A selectively responsive device adapted to respond to all codes of aplural-digit code system and adapted to enable operation of anelectrical circuit in responding to only one or said codes, said devicecomprising two shafts, cams on each of said shafts, means for rotatingone of said shafts in response to each pulse of each digit of saidcode,means for rotating the other of said shafts in response to only onepulse of each digit of said code, means for testing simultaneously therotated positions of at least one cam on each 'of said shafts after eachshaft has been rotated in response to each of said digits, said camspreset on said shafts in accordance with said one code and arrangedthereby to assume predetermined rotated positions for each digit of saidone code,

said means operative upon testing said cams in said predeterminedrotatedpositions successively for each digit of said one code to enableoperation of said circuit.

12. A selectively responsive device adapted to respond to all codes of aplural-digit code system and adapted to enable operation of anelectrical circuit in responding to only one of said codes.

said device comprising two parallel shafts, a plurality of first camsspaced along one shaft, a plurality of second cams spaced along theother shaft, some of said first cams paired with some of said secondcams, means for rotating one of said shafts in response to each pulse ofeach digit of said code, means for rotating the other of said shafts inresponse to only the first pulse of each digit of said code, means fortesting the relative rotated positions of said paired cams at theconclusion of rotation of said shafts in response to each digit, saidaired cams preset on said shafts in accordance with said one code andarranged to assume predetermined relative rotated positions for eachdigit of said one code, said means operative upon testin said pairedcams in said predetermined relative rotated positions successively foreach digit of said one code to enable operation of said circuit.

13. A selectively responsive device adapted to respond to all codes of aplural-digit code system and adapted to enable operation of anelectrical circuit in responding to only one of said codes,

1 1 said spring means after rotation thereof in response to each digit,means for rotating the other of said shafts in response to only thefirst pulse of each digit of said code, means for testing the relativerotated positions of said paired cams at the conclusion of rotation ofsaid shafts in response to each digit, said paired cams preset on saidshafts in accordance with said one code and arranged to assumepredetermined relative rotated positions for each digit of said onecode, said means operative when said paired cams. are tested in the saidpredetermined relative rotated positions upon each such test for eachdigit of said code to retain said other shaft cumulatively advancedafter each digit to thereby enable a cam on said other shaft to closesaid contact springs to complete said signaling circuit after said twoshafts have responded to all digits of said codes.

FRANK H. HIBBARD.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date H111 Jan. 26, 1915 Boswau Dec. 14, 1915Watanable May 31, 1928 Reinhold July 30, 1946

